Hi everyone I have a massive problem that I havent seen in my tank before, I have a 130 gallon tank with a all different kinds of fish, frogs, shrimp and loaches... my tank has been running for around 6 months now and its been fine up until now...
I've just been doing my water change and found around 15 small red worms in the bucket after... is this normal as I'm worried it might kill my fish? and what are they?

I wouldn't worry about it. Sounds like they are just annelids. If that's the case, then all they are doing is eating up excess / uneaten food and stirring the substrate for you. Plus, I'm sure they make great meals for your loaches. That's my opinion.